1. Field of the Invention
The present invention relates generally to automatic high-speed bottle washer and spraying systems and more particularly to an automatic high-speed bottle washing machine for washing and sanitizing plastic returnable bottles (PRB).
2. Discussion of the Prior Art
The manufacture of returnable and refillable bottles has become widespread in both the glass and plastic bottling industries. Many countries have mandated their use in an effort to conserve energy and to keep raw material consumption to a minimum. Furthermore, commercially viable, refillable bottles and containers not only conserve energy, but help to reduce land-fill and recycling problems usually associated with disposable type plastic and glass bottles and containers. One industry in particular where the desirability of utilizing plastic reusable and refillable bottles (PRB's) is increasing, is in the soft drink beverage industry.
To be commercially viable as a refillable bottle for soft drink beverages, the PRB must retain its aesthetic and functional qualities over a minimum of ten and preferably over twenty cycles or "trips" in its lifetime. A typical cycle that a returnable/refillable plastic bottle goes through has been described in numerous patents and technical articles. For instance, U.S. Pat. No. No. 4,725,464 to Collette, describes a cycle as comprising: 1) an empty caustic wash followed by 2) contaminant inspection and product filling/capping, 3) warehouse storage, 4) distribution to wholesale and retail locations, and 5) purchase, use, and empty storage by the consumer followed by eventual return to the bottler. Presently, plastic beverage bottles made of polyesters, such as polyethylene terephthalate (PET) and copolymers thereof, acrylonitrile, and polycarbonate have the requisite physical and aesthetic qualities most desirable for producing refillable plastic containers. As is well known in the art, PET offers the best balance of properties and, cost and performance ratios.
While the plastic bottling industry has made great strides in obviating the problems associated with cleaning and washing of the PRBs during a typical cycle, problems still exist with currently existing bottle washing machines. For instance, many of the existing machines for washing plastic returnable bottle (PRB) include one or more pre-treatment steps before carrying out an internal and/or external spray treatment. One such washing machine described in U.S. Pat. No. 4,154,624 provides for the pre-treating of the PRB by soaking each bottle in a water pre-softening bath or caustic solution pre-softening bath. The goal of pretreating each bottle is to remove coarse soils and residues from the beverages or products. Often these pre-softening steps are time-consuming and reduce the throughput desirable in high-output automatic PRB washing machines. In addition, the pre-softening treatment with high-temperature baths may cause premature shrinkage of the PRB, or induce stress crack failure in non-oriented portions of the bottle.
After pretreating, the PRB's are usually conveyed to an in-line or rotary carrier where they are held in place and subject to additional various external and internal spraying by additional detergents, air, and water. U.S. Pat. No. 4,125,120 discloses an inline conveyor system for washing light weight plastic bottles with a plurality of insertable spray wands. A conveyor advances in a stepwise manner and an entire manifold of nozzles is elevated by a pair of hydraulic cylinders attached to lift bars. U.S. Pat. No. 4,080,974 discloses an inline conveyor having a plurality of bottle carriers which receive the bottles in an inverted position and which are equipped with a plurality of moving spray nozzles which accompany, but which are not inserted in the bottle, along a portion of its travel for spraying and rinsing.
U.S. Pat. No. 3,226,757 and European Patents 0 265,343 and 2 607,127 disclose a bottle cleaning machine which uses a mechanism for inverting the bottles for placement into a plurality of bottle carriers and insertable wands for blowing or rinsing the bottles. U.S. Pat. No. 5,135,014 discloses a bottle washer with multiple size carriers having a sorting mechanism, a device for inverting the bottles, an inline carrier having a plurality of bottle carriers with a holddown means for adjusting the carrier to various sized bottles, and interior and exterior spray nozzles for cleaning the interior and exterior of the bottles. A spray nozzle is inserted inside the bottle, although it does not move with the bottle. The conveyor is advanced step wise on an intermittent basis and a plurality of nozzles are inserted into the bottles at each step. U.S. Pat. No. 3,534,749 discloses a rotating turntable having a plurality of bottle holding stations which are positioned above the spray nozzles. As the containers are rotated inside the spray cabinet, they are subject to both interior and exterior sprays for cleaning.
One problem associated with current soaking and spray washing machines is that many bottles are subject to stress crack failure by reason of the combination of the high temperature wash solution, the caustic nature of the solution, and the way they are handled. Other automated bottle washing systems provide mechanisms for handling containers, for example, by cradle (U.S. Pat. No. 4,080,974), or by basket (U.S. Pat. No. 4,154,624), as the bottles are being conveyed or transferred through the wash treatment. Both scuffing and stress crack failure occur in these mechanisms as the bottles rub or brush against each other or against the holders or cages in which they are transported.
Other prior art bottle washing machines which provides for the rotation of the bottles as they are being cleaned include U.S. Pat. No. 4,461,054 which discloses a device for rotating and cleaning containers with particulate matter by inserting a spray nozzle into bottles as they are rotated. During the cleaning operation the bottles are reciprocated downwardly into the containers for the cleaning step. Similarly, U.S. Pat. No. 4,133,340 discloses a rotating turntable for rotating a workpiece which is cleaned on the inside with spray nozzle having a plurality of orifices of and on the outside by spray nozzles placed on wands. In both of these references there is no movement of the rotating bottle.
Several other types of bottle washing systems use vertical carousels that are adapted to be connected to inline conveyors. U.S. Pat. Nos. 4,944,810 and 4,834,123 disclose vertical carousels having paddles which engage the lower portion of the bottle and urge it inwardly over a spray nozzle for cleaning. U.S. Pat. No. 3,302,655 discloses a similar concept without the nozzle penetration, but including exterior washing of the bottle with nozzles.
In view of the above-mentioned limitations and disadvantages of the bottle handling devices found in current automated bottle washers, there is accordingly a need to provide an apparatus for holding and rotating bottles or containers in a manner that minimizes the thermal stress in the neck areas and scuffing of the shoulder base regions and that does not require any sort of retaining or locking means.
Furthermore, it would be highly desirable for a high-speed bottle washing machine to provide for a spray nozzle that discharges fluid jets in a predetermined pattern such that when in combination with a rotating bottle, hard to reach soils accumulated at the bottom of a bottle can be effectively cleaned in shorter periods of time. Moreover, it would be highly desirable to provide for a high-speed bottle washing machine with moving bottle carriers and wash nozzles which are inserted as the bottle is rotated and moved and furthermore, one that performs the process of washing a PET bottle in a 20 second cycle with aggressive mechanical impingement of a caustic wash solution.